A conventional example of superresolution in digital holography is related to placing an diffraction grating behind an object to be observed to bend the diffraction wave at a large angle and recording a synthetic hologram, so as to produce a reconstructed image with spatial resolution which overcomes the diffraction limit of a normal aperture optical system. A conventional synthetic aperture technique associated with digital holography enables generation of a great amount of holographic recording for promoting spatial resolution and phase sensitivity of reconstructed images by using mechanical moving image sensors or spatial-multiplexing methods, such as incoherent light property, spatial light modulator-based method, using an ultra-short pulsed laser combined with a time- and angular-multiplexing methods, applying a time-multiplexing method and a galvo-mirror scanning method. However, the spatial resolution and phase sensitivity of the reconstructed images are desired to be further improved.